Re: Is an over-sized salt cell a wise investment for a pool owne
What is being said is contrary to what I was taught, that it's not necessarily how hard you drive the unit but is the combination of the factors of power, water friction, chemistry and temperature changes that effect cell life.
The temp concern is not a rapid change type, such a condition is not normally encountered. With the exception of water, AFAIK, all matter expands and contracts at specific rates and amounts as temps rise and fall, respectively. The difference when two different materials are bonded, so there is direct contact, will stress that bond.
In the case of, say, a bimetalic strip as used in a thermostat, the strip will bend a measurable amount due to their being ductile. In the case of a cell blade, one of the two materials, the metal or the coating, and I don't know which, one will shrink more than the other. This will stress the bond. It has to. Ruthenium Oxide, according to my having Googled it for some time, last night and this morning is in a crystalline form when used for cell manufacturing. If the makers of cell blade use a ceramic matrix to bond it to the blade and it has some kind of elasticity, I can see it surviving. Neither ceramics nor crystals are my areas of expertise but I have never heard of either being ductile or elastic.
I do know that crystals have aligned molecules or atoms, depending on whether they are elemental or molecular. Many ceramics are not, such as most glass but many are. Exert pressure on either and they break along fracture lines. Some ceramics are partly crystalline.
My understanding is the coating is to prevent corrosion, not some catalytic process. The electrical current that flows between each set of plates, if no salt was in the water, would simply produce Oxygen and Hydrogen. Since we want chlorine, we add salt. The same charge splits the salt molecules as well as water molecules. The use of the coating is not to protect the titanium blade from the chlorine being produced, but rather from the caustic byproducts that cause our pH to rise. This may one of the more significant factors in a salt cell's life and by spreading the generation over a larger surface, may result in a longer continuous use life. That being said, since many close their pools due to cold weather, the temp concerns, I think are still valid.
I am not a scientist. I am a pool guy. I am not qualified in stating definitively, with credentials, reports, research, etc... usually disclaimer stuff. I have been taught and I have looked for information, just as any one of us can do. I know I have customers that don't want the cell brought in at closing and those that do. I know I have replaced the cells of those haven't brought them in, both cells my then employer sold as well as others. I know I have yet to have to replace any of the cells I have been bringing in for years. The number of them is not large, maybe 6 or 7 so, IMHO, that doesn't make for a definitive sample, yet. If the cells for those customers last another few years, they will be approaching the 10K hours of use. That makes me go hmmm.
Scott